Hi Manoj,
Can you check the following SPRO node for the invoice reversal process-
SPRO--> SAP Utilities --> Invoicing---> Basic Settings----> Define Basic Settings for Reversal Invoicing
Reversal Options: Clearing Reversal
RevClearCheck single-
Post Clearing Amt-
Ideally, the value should be "Automatic Clearing reversal (with Partial Reversal)" and Retain Distribution to Accounts respectively.
Hope it helps...
Thanks,
Amlan